Aerial for use in wireless signaling



July 26, 1932.

c. s. FRANKLIN AERIAL FOR USE IN WIRELESS SIGNALING Original Filed June12, 1924 l wh. l l l h I u a r 1 my m a 1 a I rJa T 4 n H m f T a T Fr-I. c 0 no LA I/ A CHARLES S. FRANKUN INVENTQR QLQ/flm ATTORNEYPatented July 26, 1932 UNITED STATES PATENT oFFicE CHARLES SAMUELFRANKLIN, OF BUCKHURST HILLENGLAND, ASSIGNOR TORADIO CORPORATION OFAMERICA, A CORPORATION OF DELAWARE AERIAL FOR USE IN WIRELESS SIGNALINGApplication filed June 12, 1924, Serial No. naeseana in Great BritainJune 21, 1923. Renewed I January 5, 1931.

This invention relates to improvements in aerials for use in wirelesssignaling and is particularly applicable for use with short waves.

In the accompanying drawing which is only illustrative of my invention,Figure 1 indicates an antennacomprising a pair of aerial systems eachsystem consisting of a plurality of cophasally excited wires or rods.

Figure 2 illustrates apparatus for cophasally exciting the wires-or rodsof a systern such as shown in Figure 1, and

Figure ,3 indicates, in cross section, an antenna such as shown inFigure 1 and a reflector therefor for obtaining unidirectionalpropagation of electromagnetic waves.

British specification No. 128,665 describes a directional system inwhich an aerial is located at the focus of a parabolic reflectorconsisting of two or more sets of rods arranged on a parabolic surface,each rod being in tune with the aerial. To obtain really sharpdirectional effects with such a system it is necessary that thedimensions of the reflector should be very large compared with the wavelength both in the horizontal and vertical directions. Moreover, whenonce the reflector has been erected it is not capable of being readilyextended.

According to the present invention I construct an aerial of a number ofvertical wires or rods spaced a fraction of a wave length apart in aplane which is at right angles to the desired direction of working. Thewires or rods are connected together at the top and bottom and each rodtogether with the wires connecting it to the top and bottomof the nextrod is in tune with the waves to be used when'in its position in theaerial. The actual length will depend upon the spacing and to someextent upon the number-of vertical rods used.

Such an aerial system can be extended indefinitely without appreciablyaffecting the tune. By making this system of a length which is severaltimes the wave length of the waves employed very sharp transmission orreception in a horizontal plane is obtained, the directional effectbeing a function of the length of the system relative to the wavelength. Moreover, by arranging two or more such systems one aboveanother and feeding them from a common supply I can obtain slliarpdirectional eflects'in the vertical plane a so.

'Figure 1 illustrates such a system. The horizontal wires 0, d, e and f,with their connecting vertical wires as shown are two aerial systems,one, above the other. They are indicated. asbeing supported by the twomasts or towers A and B. p

Each of the aerial systems 0, d, and e, f, associated, are in tune inthe vertical direction with the wave to be transmitted or received. Thetwo systems are coupled together electrostatically through the smallcondensers is shown between the horizontal wiresd and e. In practice thecapacity between. the wires d and e is usually sufficient as a couplingcondenser. One, two, three,

. or more systems can be used above each other,

each coupled to the one above it electrostatically, or in an equivalentmanner.

Oscillations produced in anyone of the systems will thenproduceoscillations'in the systems above and below. The lengths of thevertical members and the coupling ca- 'pacities should be so adjustedthat the currents are in the same phase in each system.

Such an aerial system is capableof extension in the vertical andhorizontal directions without afiectingiappreciably the natural tuneofthe aerial. If fed correctly from a transmitter the currents in allthe vertical members of theaerial will all be in the same phase, and theaerial will radiate two beams in opposite directions, and at rightangles to the plane of the aerial.

The concentration of the radiation is a simple function of thedimensions of the aerial both vertically and horizontally.

It is desirable that no oscillations in the aerial in the'horizontaldirection should be allowed as these would representa loss of energy.The aerial may bese parated intounits, as, for instance, by introducingbreaks into the horizontal wires; or'resistancesm, Figure 1, inserted inthe horizontal members will suppress any such oscillations.

I have found that withan aerial which is large compared with the wavelength in order to produce currents in all vertical members ofsubstantially the same phase and intensity it is essential that powershould be fed to it at a number of points simultaneousaerial, s1milar tothe one shown in Figure 1.

A, B, C and D, are equally spaced feeding points which are connectedeach through a condenser and the secondary of a transformer to earth ora balancing capacity. The primaries of the transformers a, Z), 0 and (Z,are each connected to a cable; Separate cables of equal length,orequivalent length electrically may be used, or they may be. connectedas shown in Figure 2 so that the length from any transformer to thegenerator isthe same. It is necessary for efficient working that noreflection of the oscillations transmitted through the cable by thegenerator should take place at the feeding points. This can be attainedby arranging the ratio of the transformers so that the effectiveresistance of each portion of the aerial fed by the transformer asapplied to the cable is equal tothe critical resistance required at thecable terminals to prevent reflection. Under these conditions, noreflections will take place, and no stationary wave'effects will beproduced in the cables. V

I have found that cables built up ofparallel tubes or rods like a Lecherwire system and enclosed in metal conduits are best and give a very highefficiency. It is sometimes convenient to insert the transformers in thecentre of the vertical portions of the aerial, and if the resistance ofthe aerial is equal or nearly equal to the critical resistance of thecable, the cable may be directly connected in the vertical memberswithout having recourse to transformers. The secondaries of thetransformers may also be inserted between the sections of the aerial, e.g. between the wires al and 6 (see Figure 1).

p I have found that two aerial systems such as described in Figure 1arranged in parallel planes one behind the other and spaced aquarter'wave length or an odd multipleof a quarter-of a wave lengthapart maybe used. Such a, system is shown diagrammatically in Figure 3where the apparatus marked 0, d, e, f

is an aerial system such as shown in Figure 1 and, the unletteredapparatus illustrates sim- 1lar apparatus one-quarter wave length or anodd multiple of a quarter wave length apart from the aerial. If one isused as a transmitter the other functions as a reflector andunidirectional transmission or re ception with any desired degree ofconcentration is obtained. in this combination the transmitting aerialmay if desired be smaller in height than the reflecting aerial. As thereflecting aerial does not require any power feeding arrangements it mayeasily be eX- tended vertically several wave lengths and greatconcentration in the vertical direction may thus be obtained. Onepossible ar 'ran'gement is a transmitting aerial of low height comparedwith the wave length. in combination with a reflector high compared withthe wave length arranged in the form of a cylindrical parabola with itsfocal line horizontal and coincident with the transmitting aerial. V a

As a practical indication of the dimensions and results to he obtainedfrom such aerials as described, I give the following For an aerial asshown in Figure 1, I find that a practical horizontal spacing betweenthe vertical members is of the wave length and for this spacing thedistance between the horizontal members (i. e. the distance 0 d or e fin Figure 1) is about one-third of the wave length. Using a combinationof a transmitting aerial and reflecting aerial I find that with anaerial one'square wave length in area the energy radiated or received onaline at right angles to the aerial is ten times that which would beradiated or received by an ordinary aerial radiating the same totalenergy. Also that for aerials of more than one square wave length theeffect is practically proportional to the area.

An aerial of 10 square wave lengths will give 100 times the energy inthe required direction, and would receive from that direction 100 timesthe energy received by an ordinary aerial. The combination at boththetransmitting and the receiving station of aerials of 10 square wavelengths provided with reflectors will give 10,000 times the energy'obtained with ordinary aerials. If the aerials are one wave length highand ten wave lengths wide practically no energy will be radiated orreceived outside an angle of 5 to 7 from the direction joining thestation.

Having now particularly described and ascertained thenature of'my saidinvention and in what manner the same is tobe performed, I declare thatwhat I claim is r 1. An aerial for directional wireless telegraphy andtelephony comprising a number of vertical rods or wires, the rods orwires being connected together by horizontal wires, said wires and rodsforming a radiating surface, a'source of oscillations, and means forsupplying oscillations to the rods or wires, simultaneously and in thesame phase so that all of the wires of the aerial oscillate in phase, ata number of points equi-distant from said source.

2. An aerial for directional wireless telegraphy and telephony having aradiating surface made of a number of units assembled above one anotherand coupled together, said units lying in a single plane, and each unitcomprising a number of vertical rods or wires connected together byspaced horizontal wires, substantially as described.

3. An aerial according to claim 1 and having resistances inserted atpoints along the horizontal connecting wires to prevent oscillationstaking place in the aerial in the horizontal direction while allowingoscillations in the vertical direction.

4. The combination of an aerial as described in claim 2 with oscillationgenerator, and a cable feeder system for supplying oscillations to theaerial simultaneously and in the same phase at a number of pointsequidistant from said generator.

5. An aerial for directional wireless telegraphy and telephony made of anumber of i units assembled above one another and capacitively coupledtogether, each unit comprising a number of vertical rods or wiresconnected together by horizontal wires, a second aerial arrangedparallel to said first mentioned aerial, said first mentioned aerialacting as a transmitting unit and said other aerial acting as areflecting unit for the purpose of obtaining unidirectional working.

6. The combination of an aerial for directional wireless telegraphy andtelephony comprising a number of vertical rods or wires arranged in asingle plane, means for capaci tively connecting the rods or wirestogether, with a similar aerial in a parallel plane at least equal insize to said first mentioned aerial and cooperatively shieldedtherewith, one of said aerials being a transmitting aerial and saidother aerial being a reflecting aerial.

7. An aerial for directional wireless telegraphy and telephonycomprising a number of vertical rods or wires connected together byspaced horizontal wires combined with means for supplying oscillationsto the aerial simultaneously in the same phase at a number of pointsequidistant from said last mentioned means, each of said rods togetherwith its associated horizontal wires being in tune with said supplyoscillations and a reflecting aerial associated with said firstmentioned aerial.

8. An aerial for directional wireless telegraphy andtelephony made of anumber of prising a number of Vertical rods or wires connected togetherby spaced horizontal Wires, and a similar aerial associated with saidfirst mentioned aerial.

9. An aerial for directional wireless telegraphy andtelephony'comprising a system,

said system'comprising' a grip of'p'ar'allel straight wires arranged ina single plane, and another system comprising a group of parallel wiresarranged'in the sameplane the wires of the systems being Icapacitivelycoupled together, and means for exciting the Wires of both groupscophasally.

10. An antenna comprising apair of systerns spaced apart an odd numberof quarter Wave lengths each system comprising a pair of groups ofparallel straight wires, the Wires of pairs of groups beingca-pacitively coupled together, and means for-exciting all of the wiresof one of the systems substantially cophasally. l

11. An antenna system 'comprisinga wire, a plurality of radiating rodslying in one plane connected thereto, Etl'lOtllGPWlI'B, a-plurality ofradiating rods lying in the sa-id same plane connected to "said otherwire, and condensers'between said wires. g I i 12. An antenna systemcomprising awire, a-plurality of parallel radiating rods lying in oneplanearranged perpendicularfito "and connected to said Wire; anotherwire, a-p1u rality of parallel rods lying in thesaid' same planearranged perpendicular to and connected to said other wire, condensersbetween the Wires and means for exciting the ro'ds cophasally.

tem, a plurality of aerials arrangedintine plane, each of said aerialsoscillating at a predetermined phasewith respect to each other so that abilateral sending characteristic a direction perpendicular tothe planeof-the aerials is obtained, and a reflector unexcited except for theexcitation produced by the aerials in a plane parallel to the plane ofthe aerials for causing said aerials to have a uni lateral directionalchracteristic.

14. A unidirectionl radiating 'system'coinprising a plurality ofantennae arranged in one plane and excited so that a bilateral radiatingcharacteristic in a direction substantially at right angles to the planeof the antennae is obtained, and a reflector uncoupled from'the antennaein a plane parallel to the plane of the antennae for reflectingwaves'mdiated in one direction by the antennae in such radiatingcharacteristic in directions substantially at right angles to the planeof the antennae and means uncoupled from said antennae for reflectingthe waves radiated in one of said'bilateral directions-by'each offtheantennae to produce a unidirectional radiating r I e5 13. Incombination, ina transmitting syscharacteristic'in the other of saidbilateral directions. a

16. A unidirectional radiating system comprising at least three antennaearranged in substantially the same plane and excited to produce abilateral radiating characteristic in a direction substantially at rightangles to the plane of the antennae and means uncoupled from saidantennae for reflecting the waves radiated in one of said bilateraldirections by each of the antenna to produce a unidirectionalcharacteristic in the other of said bilateral directions.

.17. A unidirectional radiatingsystem comprising at least three antennaearranged in one plane and excited so that a bilateral radiatingcharacteristic in a direction substantially at right angles to the planeof the antennae is obtained, and a reflector uncoupled from saidantennae in a plane parallel to the plane of the antennae for reflectingwaves radiated in one direction by the antennae in such a manner thatthe entire system comprising the antennae and reflector has aunidirectional radiating characteristic in a direction away from theplane of the antenna on the side opposite the reflector.

18. In combination, a plurality of vertical transmitting antennaearranged in a straight line and a reflector uncoupled from said antennaearranged in a plane parallel to said line.

19. In combination, a plurality of radiating antennae arranged in asingle plane and excited so that radiation therefrom is pre dominantlybidirectional and substantially perpendicular to the plane of theantennae; and a reflector, comprising a plurality of tuned antennaearranged ina planeparallel to the plane of the radiating antennae,uncoupled therefrom, and unenergized except for the energization causedby radiated energy from the radiating antennae, for making radiationfrom the radiating antennae unidirectional.

20. In an arrangement for directional radio communication thecombination with an antenna arrangement comprising at least threeantennae positioned in an approximately straight lineand at equaldistances from one another; of a reflecting screen built up ofelectrical conductors and arranged at one side ofthe said antennaarrangement and in parallel to the row of main antennae; only theantenna arrangement'of said combination be ing supplied with highfrequency energy. 7

21. In an arrangement for directional radio communication thecombination with a main antenna arrangement comprising at least threeantennae tuned to a' given frequency and positioned'in an approximatelystraight line and at equal distances from one another; of a'reflectingscreen built up of a plurality of antennae tuned to the same frequencyand arranged at one side of the said plurality of suspended conductorswith reactors in series arranged in parallel to therow of main antennae,the said conductors with the said reactors being tuned to the samefrequency; and, high frequency apparatus connected to the said antennaarrangement. 7

28. In an arrangement for directional radio communication thecombination with an antenna arrangement for bilateral directionalemission and reception of waves; comprising at least three substantiallyperpendicular antennae disposed in an approximately straight line andbeing tuned to a given frequency; of a reflecting screen built up of aplurality of substantially perpendicular conductors arranged at one sideof said antenna arrangement and substantially parallel thereto; saidscreen corresponding an appreciable fraction of or-greater than a Wavelength of the wave corresponding to the natural frequencyof the antennaeofthe main antenna arrangementgand of high frequency apparatus connectedto the said antenna arrangement. a a 1 24. In an arrangement fordirectional radio communication the combination with an antennaarrangement for bilateral directional emission and reception of wavescomprising at least three substantially perpendicular antennze tuned toa given frequency and positioned in a substantially straight line and atequal distances from one another; of

a reflecting screen built up of a plurality three antennaepositioned inan approximately straight line and at equal distances from one another;of a reflecting screen built up of electrical conductors and arranged atone side of the said antenna arrangement and in parallel to the rowofniain antennae; and, high frequency apparatus'connected to the saidantenna arrangement. H r V 26. In an arrangement for directional radiocommunication the combination with a main antenna arrangement comprisingat least three antennae tuned to a given frequency and positioned in anapproximately straight line and at equal distances from one another; ofa reflecting screen built up of a plurality of antennae tuned to thesame frequency and arranged at one side of the said antenna arrangementand in parallel to the row of main antennae; and high frequencyapparatus connected to the said main antenna arrangement.

27. In an arrangement for directional radio communication thecombination With an antenna arrangement comprising at least threeantennae positioned in an approximately straight line and at equaldistances from one another; of a reflecting screen built up ofelectrical conductors and arranged at one side of the said antennaarrangement and in parallel to the row of main antennae; and, highfrequency transmitting apparatus connected to the said antennaarrangement.

28. In an arrangement for directional radio communication thecombination with a main antenna arrangement comprising at least threeantennae tuned to a given frequency and positioned in an approximatelystraight line and at equal distances from one another; of a reflectingscreen built up of a plurality of antennae tuned to the same frequencyand arranged at one side of the said antenna arrangement and in parallelto the row of main antennae; and high frequency transmitting apparatusconnected to the said main antenna arrangement.

CHARLES SAMUEL FRANKLIN.

